In a polymer electrolyte fuel cell, an ion exchange membrane has exchange groups for hydrogen ions in molecules thereof, and functions as an ion conductive substance by being saturated and hydrous. Then, when the ion exchange membrane is dried, ion conductivity thereof decreases, and cell performance of the fuel cell significantly decreases. Accordingly, in order to prevent the ion exchange membrane from being dried, unreacted gas is humidified in advance by using a temperature-humidity exchanger with a structure in which water and the unreacted gas are caused to flow on both surfaces of a moisture permeable membrane such as a solid polymer electrolyte membrane.
This temperature-humidity exchanger has a construction in which the moisture permeable membrane is sandwiched by a separator provided with a channel groove through which the unreacted gas is caused to flow and the other separator provided with a channel groove through which humidification water is caused to flow. Projections opposed to a flow of the unreacted gas are disposed on bottoms of the meandering gas channel grooves formed inside of the separators by being partitioned by ribs, and the unreacted gas becomes a turbulent flow to be effectively stirred, and is brought into effective contact with the moisture permeable membrane, thereby enhancing humidity efficiency (see, for example, Patent Document 1).
However, a water supply device which prepares water heated as humidification water is separately required, resulting in extra cost. In this connection, a temperature-humidity exchanger for performing a temperature-humidity exchange between the exhaust gas exhausted from the fuel cell and the unreacted gas is proposed. With regard to the temperature-humidity exchanger concerned, a temperature-humidity exchanger composed of a first humidification block and a second humidification block is coupled to a fuel cell main body via a spacer. The air as the unreacted gas is caused to flow to the first humidification block, and further to the second humidification block, and is then supplied to an air electrode of the fuel cell main body. Meanwhile, the exhaust gas containing moisture, which is exhausted from the air electrode of the fuel cell, is introduced into the temperature-humidity exchanger, is caused to flow in a direction reverse to that of the unreacted gas, and is discharged to the outside from an exhaust gas port (see, for example, Patent Document 2).
Further, a temperature-humidity exchanger using the exhaust gas has a temperature-humidity exchange cell formed by alternately stacking mesh plates and water-holding porous bodies in order to prevent the moisture permeable membrane from being dried. The exhaust gas and the unreacted gas, which are introduced into the temperature-humidity exchange cell, are brought into contact with each other via the water-holding porous bodies, and temperatures and humidities thereof are exchanged (see, for example, Patent Document 3).    Patent Document 1: JP 11-185777 A    Patent Document 2: JP 2002-170584 A    Patent Document 3: JP 2000-164229 A